CN216699066U - Erbium doped fiber amplifier and communication system - Google Patents

Abstract

The utility model discloses an erbium-doped fiber amplifier and a communication system, wherein the erbium-doped fiber amplifier comprises: the optical fiber amplifier comprises a first input port, a first input optical power monitoring unit, a first erbium fiber, a first integrated device and a first output port, and the optical fiber amplifier comprises a second input port, a second input optical power monitoring unit, a second erbium fiber, a second integrated device and a second output port. The first signal light is input from the first input port and sequentially passes through the input optical power monitoring unit, the two-in-one integrated device, the first erbium-doped fiber and the first integrated device to the first output port; the second signal light is input from the second input port and sequentially passes through the second input optical power monitoring unit, the two-in-one integrated device, the second optical feed fiber and the second integrated device to the second output port. Two amplifiers share the two-in-one integrated device, so that the two amplifiers are integrated in the same package.

Description

Erbium doped fiber amplifier and communication system

Technical Field

The utility model relates to the technical field of optical fiber communication, in particular to an erbium-doped optical fiber amplifier and a communication system.

Background

Erbium Doped Fiber Amplifiers (EDFAs) are an important device widely used in optical communication systems. The EDFA can directly amplify optical signals without complex processes of photoelectric conversion, electro-optical conversion, signal regeneration and the like. The EDFA has the advantages of high gain, low noise, large bandwidth, electromagnetic interference resistance and the like, and is widely applied to long-distance large-capacity optical fiber communication systems.

At present, SFP (Small Form-factor plug) and QSFP (Small Form-factor plug) packaged single-path C-Band EDFA products exist in the market, and the output power can reach the level of 17dBm by using a non-refrigeration 980nm pump laser.

However, most of the existing SFP and QSFP packaged products in the market are single-path C-Band EDFA products, and only single-path/unidirectional signal optical power amplification can be realized. And the design that two paths of amplifiers are integrated in the same package cannot be realized due to the content of standard package, device size and the like.

SUMMERY OF THE UTILITY MODEL

The utility model provides an erbium-doped fiber amplifier and a communication system, and aims to solve the problem that the existing SFP and QSFP packaged products are single-path C-Band EDFA products and can only realize single-path signal light power amplification. And the design that two paths of amplifiers are integrated in the same package cannot be realized due to the limitation of the standard package, the device size and the like.

In a first aspect, the present invention provides an erbium-doped fiber amplifier comprising: the optical fiber amplifier comprises a first optical fiber amplifier, a second optical fiber amplifier, a two-in-one integrated device and a pumping unit, wherein the first optical fiber amplifier comprises a first input port, a first input optical power monitoring unit, a first erbium fiber, a first integrated device and a first output port; the second optical fiber amplifier comprises a second input port, a second input optical power monitoring unit, a second erbium optical fiber, a second integrated device and a second output port; a two-in-one integrated device for connecting the first input optical power monitoring unit and the first erbium fiber, and for connecting the second input optical power monitoring unit and the second erbium fiber; the pumping unit is connected with the two-in-one integrated device and used for providing pumping light for the first erbium fibers and the second erbium fibers; a first signal light is input from the first input port and sequentially passes through the input optical power monitoring unit, the two-in-one integrated device, the first erbium-doped fiber and the first integrated device to the first output port; second signal light is input from the second input port and sequentially passes through the second input optical power monitoring unit, the two-in-one integrated device, the second optical feed fiber and the second integrated device to the second output port.

Further, the two-in-one integrated device comprises an isolator and a WDM, the first signal light is input to the WDM through the isolator, and the WDM combines the first signal light and the pump light and outputs the first signal light; and the second signal light is input to the WDM through the isolator, and the WDM combines the second signal light and the pump light and outputs the combined light.

Further, the pumping unit includes a first pumping laser and a second pumping laser, both the first pumping laser and the second pumping laser are connected to the two-in-one integrated device, the first pumping laser is configured to provide first pumping light to combine with the first signal light, and the second pumping laser is configured to provide second pumping light to combine with the second signal light.

Further, both the first pump laser and the second pump laser adopt 980nm uncooled pump lasers.

Further, the two-in-one integrated device includes a first port for inputting the first signal light, a second port for inputting the second signal light, a third port for inputting the first pump light, a fourth port for inputting the second pump light, a fifth port for outputting the beam of the first signal light combined with the first pump light, and a sixth port for outputting the beam of the second signal light combined with the second pump light.

Further, the first integrated device includes a first isolator, a first optical splitter, and a first photodiode for output optical power monitoring, the first signal light amplified by the first optical fiber sequentially passes through the first isolator and the first optical splitter and is output to the first output port, and the first optical splitter is configured to split the first signal light to the first photodiode.

Further, the second integrated device includes a second isolator, a second optical splitter, and a second photodiode for monitoring output optical power, where the second signal light amplified by the second optical fiber sequentially passes through the second isolator and the second optical splitter and is output to the second output port, and the second optical splitter is configured to split the second signal light to the second photodiode.

Further, the optical fiber amplifier further comprises a circuit control unit, the circuit control unit is connected with the first photodiode and the second photodiode, the circuit control unit is further connected with the first input optical power monitoring unit and the second input optical power monitoring unit, the circuit control unit is used for performing function control according to input optical power and output optical power, and the function control comprises at least one of ACC, AGC and APC.

Further, the first erbium-doped fiber and the second erbium-doped fiber both adopt erbium-doped fibers with absorption coefficients of 80us models or 165us signals.

In a second aspect, the present invention further provides a communication system comprising an erbium-doped fiber amplifier, wherein the erbium-doped fiber amplifier is the erbium-doped fiber amplifier of the first aspect.

Compared with the prior art, the utility model has the beneficial effects that: the first path of optical fiber amplifier comprises a first input port, a first input optical power monitoring unit, a first erbium fiber, a first integrated device and a first output port, and the second path of optical fiber amplifier comprises a second input port, a second input optical power monitoring unit, a second erbium fiber, a second integrated device and a second output port. The first path of optical fiber amplifier and the second path of optical fiber amplifier share one two-in-one integrated device, and first signal light is input from a first input port and sequentially passes through an input optical power monitoring unit, the two-in-one integrated device, a first erbium fiber and the first integrated device to a first output port; the second signal light is input from the second input port and sequentially passes through the second input optical power monitoring unit, the two-in-one integrated device, the second optical feed fiber and the second integrated device to the second output port. From this, a two unification integrated device connects first input optical power monitor cell and first bait optic fibre, connects second input optical power monitor cell and second bait optic fibre again simultaneously for two way amplifiers all can transmit the light signal through this two unification integrated device, greatly reduces occupation space, can realize the design of two way amplifier integrations in same encapsulation, satisfies miniaturized demand.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 shows a schematic diagram of an erbium doped fiber amplifier according to an embodiment of the present invention;

FIG. 2 shows a schematic diagram of an erbium doped fiber amplifier according to another embodiment of the present invention;

FIG. 3 shows a schematic diagram of a two-in-one integrated device of an erbium doped fiber amplifier according to an embodiment of the present invention;

FIG. 4 shows a schematic diagram of a first integrated device of an erbium doped fiber amplifier according to an embodiment of the present invention;

FIG. 5 is a schematic diagram showing the function control of an erbium-doped fiber amplifier according to an embodiment of the present invention

11. A first input port; 12. a first input optical power monitoring unit; 13. a first bait fiber; 14. a first integrated device; 141. a first isolator; 142. a first beam splitter; 143. a first photodiode; 15. a first output port; 21. a second input port; 22. a second input optical power monitoring unit; 23. a second bait fiber; 24. a second integrated device; 25. a second output port; 30. a two-in-one integrated device; 40. a pumping unit; 41. a first pump laser; 42. a second pump laser.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the utility model herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

Referring to fig. 1, an embodiment of the present invention provides an erbium-doped fiber amplifier, including: the optical fiber amplifier comprises a first optical fiber amplifier, a second optical fiber amplifier, a two-in-one integrated device 30 and a pumping unit 40, wherein the first optical fiber amplifier comprises a first input port 11, a first input optical power monitoring unit 12, a first erbium-doped fiber 13, a first integrated device 14 and a first output port 15; a second optical fiber amplifier, which includes a second input port 21, a second input optical power monitoring unit 22, a second optical erbium fiber 23, a second integrated device 24 and a second output port 25; a two-in-one integrated device 30 for connecting the first input optical power monitoring unit 12 and the first erbium fiber 13, and for connecting the second input optical power monitoring unit 22 and the second erbium fiber 23; a pumping unit 40 connected to the two-in-one integrated device 30 for providing pumping light to the first and second erbium fibers 13 and 23; a first signal light is input from the first input port 11 and sequentially passes through the input optical power monitoring unit, the two-in-one integrated device 30, the first optical feed-through 13, the first integrated device 14 to the first output port 15; a second signal light is input from the second input port 21 and sequentially passes through the second input optical power monitoring unit 22, the two-in-one integrated device 30, the second optical feed fiber 23, the second integrated device 24 to the second output port 25.

Specifically, the erbium-doped fiber amplifier of the embodiment is a C-band erbium-doped fiber amplifier, and the erbium-doped fiber amplifier is packaged by QSFP-DD. The QSFP-DD package can realize standardized product design including electrical interface definition, software communication protocol and the like. In this embodiment, the first erbium-doped fiber 13 and the second erbium-doped fiber 23 both use erbium-doped fibers with absorption coefficients of 80us models or 165us signals, which can reduce the length of the optical fibers and reduce the saturation of the optical fibers and the difficulty in manufacturing the optical path process.

By implementing the embodiment, a first optical fiber amplifier and a second optical fiber amplifier are provided, the first optical fiber amplifier includes a first input port 11, a first input optical power monitoring unit 12, a first optical erbium-doped fiber 13, a first integrated device 14, and a first output port 15, and the second optical fiber amplifier includes a second input port 21, a second input optical power monitoring unit 22, a second optical erbium-doped fiber 23, a second integrated device 24, and a second output port 25. The first optical fiber amplifier and the second optical fiber amplifier share one two-in-one integrated device 30, and first signal light is input from a first input port 11 and sequentially passes through an input optical power monitoring unit, the two-in-one integrated device 30, a first erbium fiber 13 and a first integrated device 14 to a first output port 15; the second signal light is input from the second input port 21 and sequentially passes through the second input optical power monitoring unit 22, the two-in-one integrated device 30, the second optical feed fiber 23, the second integrated device 24 to the second output port 25. Therefore, a two-in-one integrated device 30 is connected with the first input optical power monitoring unit 12 and the first erbium optical fiber 13, and is connected with the second input optical power monitoring unit 22 and the second erbium optical fiber 23, so that the two amplifiers can transmit optical signals through the two-in-one integrated device 30, the occupied space is greatly reduced, the design of the two amplifiers integrated in the same package can be realized, and the requirement of miniaturization is met.

In an embodiment, referring to fig. 2, the two-in-one integrated device 30 includes an isolator to which the first signal light is input, and a WDM that combines the first signal light with the pump light and outputs the combined signal light; and the second signal light is input to the WDM through the isolator, and the WDM combines the second signal light and the pump light and outputs the combined light. Specifically, the isolator is used for realizing reverse optical isolation, that is, signal light can only go from the input end to the output end and can not go back to the input end from the output end, and an optical signal going back to the input end from the output end is isolated. The first signal light enters the isolator through the first input optical power monitoring unit 12 and then enters the WDM through the isolator, and similarly, the second signal light enters the isolator through the second input optical power monitoring unit 22 and then enters the WDM through the isolator. Wdm (wavelength Division multiplexing) is a wavelength Division multiplexer, and is used for coupling and combining optical carrier signals of two or more different wavelengths together and coupling the optical carrier signals into the same optical fiber for transmission. The WDM of the present embodiment is a WDM pad for combining and coupling the first signal light and the pump light into the first erbium fiber 13 for gain amplification, and also for combining and coupling the second signal light and the pump light into the second erbium fiber 23 for gain amplification. Therefore, the isolator is integrated with the WDM through the two-in-one integrated device 30, the size of the device is reduced, more importantly, the first path of optical fiber amplifier and the second path of optical fiber amplifier share the integrated device, the first signal light and the second signal light can transmit light signals through the integrated device, the device is saved, and the occupied space is greatly reduced.

In an embodiment, referring to fig. 2, the pumping unit 40 includes a first pumping laser 41 and a second pumping laser 42, both the first pumping laser 41 and the second pumping laser 42 are connected to the two-in-one integrated device 30, the first pumping laser 41 is configured to provide first pumping light to combine with the first signal light, and the second pumping laser 42 is configured to provide second pumping light to combine with the second signal light. Each optical fiber amplifier is configured with a pump laser, which is a first pump laser 41 and a second pump laser 42, respectively, the first pump laser 41 emits a first pump light, which is combined with the first signal light by the WDM in the two-in-one integrated device 30, and the second pump laser 42 emits a second pump light, which is combined with the second signal light by the WDM in the two-in-one integrated device 30. The two-way amplifier uses a miniaturized 3PIN PIN 980nm non-refrigeration pump laser, the size is small, the power consumption is low, the power consumption of the whole machine can be controlled to be less than 3.0W, and the first pump laser 41 and the second pump laser 42 both use 980nm non-refrigeration pump lasers.

In other embodiments, the pump unit 40 includes a pump laser and a pump beam splitter, and the pump light provided by the pump laser is split by the pump beam splitter to obtain a first pump light and a second pump light, where the first pump light is combined with the first optical signal, and the second pump light is combined with the second optical signal. Through the mode that adopts pump laser and pump beam splitter, can only use a pump laser can provide two routes of pump light to be used for first erbium fiber 13 of pumping and pumping second erbium fiber 23 respectively, saved a pump laser, reduce occupation space, reduce the volume, satisfy miniaturized demand.

In a specific implementation, referring to fig. 3, the two-in-one integrated device 30 has six ports, namely four input ports and two output ports, the first to fourth ports are input ports, and the fifth and sixth ports are output ports. Specifically, the two-in-one integrated device 30 includes a first port for inputting the first signal light, a second port for inputting the second signal light, a third port for inputting the first pump light, a fourth port for inputting the second pump light, a fifth port for outputting the beam of the first signal light combined with the first pump light, and a sixth port for outputting the beam of the second signal light combined with the second pump light. The first port and the second port respectively introduce the first signal light and the second signal light into the isolator, the third port and the fourth port respectively introduce the first pump light and the second pump light into the WDM, and the fifth port and the sixth port respectively introduce the combined light beams. The size of the two-in-one device is required to be higher by <2.2mm (diameter) × 23m (length), and the functional integration level is high.

In an embodiment, the first input optical power monitoring unit 12 includes an optical splitter and a photodiode (not shown in the figure), the first signal light is guided out by the optical splitter to a beam of optical signal and enters the photodiode, and the photodiode performs optical-to-electrical conversion to convert the optical signal into an electrical signal and provide the electrical signal to the circuit control unit for power monitoring. The circuit control unit is a control circuit having a monitoring function, for example, a circuit composed of an MCU and its peripheral circuits. Similarly, the second input optical power monitoring unit 22 also includes an optical splitter and a photodiode, and the optical splitter splits the second optical signal to the photodiode, and the circuit control unit performs power monitoring after the photodiode is converted. Therefore, in this embodiment, the first input optical power monitoring unit 12 and the second input optical power monitoring unit 22 can monitor the input optical power, and have hardware and software control functions, so that the functional requirements of Disable control, EyeSafe power control, monitoring alarm, module reset, module in-place monitoring, and the like can be met.

In an embodiment, referring to fig. 4, the first integrated device 14 includes a first isolator 141, a first optical splitter 142, and a first photodiode 143 for outputting optical power monitoring, the first signal light amplified by the first optical feed fiber 13 sequentially passes through the first isolator 141 and the first optical splitter 142 to be output to the first output port 15, and the first optical splitter 142 is configured to split the first signal light to the first photodiode 143. Similarly, the second integrated device 24 includes a second isolator, a second optical splitter and a second photodiode for monitoring output optical power, the second signal light amplified by the second optical fiber 23 sequentially passes through the second isolator and the second optical splitter and is output to the second output port 25, and the second optical splitter is configured to split the second signal light to the second photodiode. Specifically, the first isolator 141 is used to realize reverse optical isolation, and the second isolator is also used to realize reverse optical isolation. The first optical splitter 142 and the first photodiode 143 constitute a first output optical power monitoring unit, and the second optical splitter and the second photodiode constitute a second output optical power monitoring unit. The amplified first signal light enters the first optical splitter 142 through the first isolator 141, a part of the light beam is introduced into the first photodiode 143 by the first optical splitter 142 for photoelectric conversion, and the other part of the light beam is introduced into the first output port 15 for output. Similarly, the amplified second signal light enters the second optical splitter through the second isolator, a part of the light beam is introduced into the second photodiode by the second optical splitter for photoelectric conversion, and the other part of the light beam is introduced into the second output port 25 for output. The device size requirements of the first integrated device 14 and the second integrated device 24 in this embodiment are <2.7mm (diameter) × 17m (length) high, and functional integration is high. On one hand, the first integrated device 14 and the second integrated device 24 integrate the isolator and the optical power monitoring unit, so that the size of the device is reduced, the occupied space is reduced, on the other hand, the optical power monitoring unit is used for monitoring the output optical power, and the input/output ends of the device realize the power monitoring function, so that the reliability and the safety of signal transmission are ensured.

In an embodiment, referring to fig. 5, the erbium-doped fiber amplifier further includes a circuit control unit, the circuit control unit is connected to the first photodiode and the second photodiode, the circuit control unit is further connected to the first input optical power monitoring unit 12 and the second input optical power monitoring unit 22, the circuit control unit is configured to perform function control according to input optical power and output optical power, and the function control includes at least one of ACC, AGC, and APC. The circuit control unit of the present embodiment acquires electrical signals, such as a voltage signal and a current signal, corresponding to the input-side optical signal through the two input optical power control units, and acquires electrical signals, such as a voltage signal and a current signal, corresponding to the output-side optical signal through the photodiodes of the two output sides. By using the electric signals corresponding to the acquired optical signals of the input side and the output side, ACC Control (Automatic current Control), AGC Control (Automatic Gain Control), and APC Control (Automatic Power Control) can be realized. The intelligent degree of the module is high, and the control is simpler. Therefore, the erbium-doped fiber amplifier of the embodiment is a 2in 1C-Band EDFA product which accords with the QSFP-DD communication protocol standard, and integrates a control circuit to realize AGC/APC/ACC function control. The functions of miniaturization, low power consumption, high output power, hot plug, two-way amplification and the like are realized; and in order to meet the miniaturization requirement, a plurality of novel miniaturized passive optical devices can be designed and developed.

An embodiment of the present invention further provides a communication system, which includes an erbium-doped fiber amplifier, where the erbium-doped fiber amplifier is the erbium-doped fiber amplifier described in the above embodiment, and details are not repeated here.

By implementing the embodiment, product standardization is realized, different communication systems can be directly used, and the increase of the demand of a module application scene is increased; the power consumption is low and is less than 3.0W, and the system does not need to consider extra heat dissipation design; the use is flexible, and the plug and play is realized; the occupied space is small, and the design difficulty of the board card of the communication system is reduced. The erbium-doped fiber amplifier in the embodiment is used as a standard QSFP-DD packaged two-way C-Band EDFA product, can support a QSFP-DD slot and a hot plug function, and can be applied to DWDM and ROADM systems of various network service providers such as 5G mobile communication, data centers and the like.

In addition, the erbium-doped fiber amplifier can realize the integration of two-path amplifiers in QSFP-DD packaging, the performance of each path of amplifier reaches the performance level of a single-path amplifier in the market, and the two paths of amplifiers can realize the performance output of gain 28 dB/output power 18 dBm. When the bidirectional communication system is applied, the two-way signal light amplification requirement can be met by one slot, because the bidirectional communication system comprises two independent amplifiers, one amplifier can achieve signal light amplification in one direction, and the other amplifier can achieve signal light amplification in the opposite direction, so that amplification in two communication directions can be achieved at one node, and the use of customers is more flexible.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (10)

1. An erbium doped fiber amplifier, comprising:

the first optical fiber amplifier comprises a first input port, a first input optical power monitoring unit, a first erbium-doped fiber, a first integrated device and a first output port;

the second optical fiber amplifier comprises a second input port, a second input optical power monitoring unit, a second erbium optical fiber, a second integrated device and a second output port;

a two-in-one integrated device for connecting the first input optical power monitoring unit and the first erbium fiber, and for connecting the second input optical power monitoring unit and the second erbium fiber;

the pumping unit is connected with the two-in-one integrated device and used for providing pumping light for the first erbium fibers and the second erbium fibers;

a first signal light is input from the first input port and sequentially passes through the input optical power monitoring unit, the two-in-one integrated device, the first erbium-doped fiber and the first integrated device to the first output port; second signal light is input from the second input port and sequentially passes through the second input optical power monitoring unit, the two-in-one integrated device, the second optical feed fiber and the second integrated device to the second output port.

2. The erbium-doped fiber amplifier of claim 1, wherein the two-in-one integrated device comprises an isolator and a WDM, the first signal light is input to the WDM through the isolator, and the WDM combines the first signal light with the pump light and outputs the combined signal light; and the second signal light is input to the WDM through the isolator, and the WDM combines the second signal light and the pump light and outputs the combined light.

3. The erbium-doped fiber amplifier of claim 2, wherein the pump unit comprises a first pump laser and a second pump laser, the first pump laser and the second pump laser are both connected to the two-in-one integrated device, the first pump laser is configured to provide a first pump light to combine with the first signal light, and the second pump laser is configured to provide a second pump light to combine with the second signal light.

4. The erbium-doped fiber amplifier of claim 3, wherein the first pump laser and the second pump laser are both 980nm uncooled pump lasers.

5. The erbium-doped fiber amplifier of claim 4, wherein the two-in-one integrated device comprises a first port for inputting the first signal light, a second port for inputting the second signal light, a third port for inputting the first pump light, a fourth port for inputting the second pump light, a fifth port for outputting the beam of the first signal light combined with the first pump light, and a sixth port for outputting the beam of the second signal light combined with the second pump light.

6. The erbium-doped fiber amplifier of any one of claims 1-5, wherein the first integrated device comprises a first isolator, a first optical splitter and a first photodiode for output optical power monitoring, the first signal light amplified by the first erbium fiber passes through the first isolator and the first optical splitter in sequence and is output to the first output port, and the first optical splitter is configured to split the first signal light to the first photodiode.

7. The erbium-doped fiber amplifier of claim 6, wherein the second integrated device comprises a second isolator, a second optical splitter and a second photodiode for output optical power monitoring, the second signal light amplified by the second erbium fiber passes through the second isolator and the second optical splitter in sequence and is output to the second output port, and the second optical splitter is configured to split the second signal light to the second photodiode.

8. The erbium-doped fiber amplifier of claim 7, further comprising a circuit control unit, wherein the circuit control unit is connected to the first photodiode and the second photodiode, the circuit control unit is further connected to the first input optical power monitoring unit and the second input optical power monitoring unit, and the circuit control unit is configured to perform a function control according to an input optical power and an output optical power, and the function control includes at least one of ACC, AGC, and APC.

9. The erbium-doped fiber amplifier of claim 8, wherein said first erbium-doped fiber and said second erbium-doped fiber each use an 80us model or 165us signal absorption coefficient erbium-doped fiber.

10. A communication system comprising an erbium doped fibre amplifier according to any one of claims 1 to 9.

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